Optimal reinforcing networks for elastic membranes
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Abstract
In this paper we study the optimal reinforcement of an elastic membrane, fixed at its boundary, by means of a network (connected one-dimensional structure), that has to be found in a suitable admissible class. We show the existence of an optimal network, and observe that such network carries a multiplicity that in principle can be strictly larger than one. Some numerical simulations are shown to confirm this issue and to illustrate the complexity of the optimal network when the total length becomes large.
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Keywords:
- Optimal networks,
- elastic membranes,
- reinforcement,
- relaxed solution,
- Golab's semicontinuity theorem.
Mathematics Subject Classification: 49J45, 49Q10, 35R35, 35J25, 49M05.Citation: -
Figure 1. Approximation of globally optimal reinforcement structures for $ m = 0.5 $, $ L = 1, \, 2 $ and $ 3 $. The upper colorbar is related to the weights $ \theta $ which colors the optimal reinforcement set on the left, whereas the lower colorbar stands for the tangential gradient plotted on the connected set on the right picture
Figure 3. Approximation of globaly optimal reinforcement structures for $ m = 0.5 $, $ L = 4, \, 5 $ and $ 6 $. The upper colorbar is related to the weights $ \theta $ which colors the optimal reinforcement set on the left, whereas the lower colorbar stands for the tangential gradient plotted on the connected set on the right picture
Figure 2. Approximation of globaly optimal reinforcement strucutres for m = 0.5, L = 1.5, 2.5 and 5 for a source consisting of two dirac masses. The upper colorbar is related to the weights θ which colors the optimal reinforcement set on the left, whereas the lower colorbar stands for the tangential gradient plotted on the connected set on the right picture
Table 1. Reinforcement values computed on a fine mesh of
elements for classical and computed connected sets for$ 10^6 $ $ m = 0.5 $ Length constraint Theoretical guesses Computed optimal networks 1 -0.179471 (radius) -0.178873 2 -0.165095 (diameter) -0.161944 3 -0.152676 (star) -0.149601 4 -0.141969 (cross) -0.138076 5 - -0.127661 6 - -0.117140 -
References
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Figure 1.
Approximation of globally optimal reinforcement structures for
,$ m = 0.5 $ and$ L = 1, \, 2 $ . The upper colorbar is related to the weights$ 3 $ which colors the optimal reinforcement set on the left, whereas the lower colorbar stands for the tangential gradient plotted on the connected set on the right picture$ \theta $ -
Figure 3.
Approximation of globaly optimal reinforcement structures for
,$ m = 0.5 $ and$ L = 4, \, 5 $ . The upper colorbar is related to the weights$ 6 $ which colors the optimal reinforcement set on the left, whereas the lower colorbar stands for the tangential gradient plotted on the connected set on the right picture$ \theta $ -
Figure 2.
Approximation of globaly optimal reinforcement strucutres for m = 0.5, L = 1.5, 2.5 and 5 for a source consisting of two dirac masses. The upper colorbar is related to the weights θ which colors the optimal reinforcement set on the left, whereas the lower colorbar stands for the tangential gradient plotted on the connected set on the right picture